Introduces scala-reflect.jar

1 files changed, 50 insertions, 0 deletions

diff --git a/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala b/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala
new file mode 100644
index 0000000000..f1fe4fc118
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+++ b/src/reflect/scala/reflect/internal/ExistentialsAndSkolems.scala
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+/* NSC -- new scala compiler
+ * Copyright 2005-2011 LAMP/EPFL
+ * @author  Martin Odersky
+ */
+
+package scala.reflect
+package internal
+
+import scala.collection.{ mutable, immutable }
+import util._
+
+/** The name of this trait defines the eventual intent better than
+ *  it does the initial contents.
+ */
+trait ExistentialsAndSkolems {
+  self: SymbolTable =>
+
+  /** Map a list of type parameter symbols to skolemized symbols, which
+   *  can be deskolemized to the original type parameter. (A skolem is a
+   *  representation of a bound variable when viewed inside its scope.)
+   *  !!!Adriaan: this does not work for hk types.
+   */
+  def deriveFreshSkolems(tparams: List[Symbol]): List[Symbol] = {
+    class Deskolemizer extends LazyType {
+      override val typeParams = tparams
+      val typeSkolems  = typeParams map (_.newTypeSkolem setInfo this)
+      override def complete(sym: Symbol) {
+        // The info of a skolem is the skolemized info of the
+        // actual type parameter of the skolem
+        sym setInfo sym.deSkolemize.info.substSym(typeParams, typeSkolems)
+      }
+    }
+    (new Deskolemizer).typeSkolems
+  }
+
+  /** Convert to corresponding type parameters all skolems of method
+   *  parameters which appear in `tparams`.
+   */
+  def deskolemizeTypeParams(tparams: List[Symbol])(tp: Type): Type = {
+    class DeSkolemizeMap extends TypeMap {
+      def apply(tp: Type): Type = tp match {
+        case TypeRef(pre, sym, args) if sym.isTypeSkolem && (tparams contains sym.deSkolemize) =>
+          mapOver(typeRef(NoPrefix, sym.deSkolemize, args))
+        case _ =>
+          mapOver(tp)
+      }
+    }
+    new DeSkolemizeMap mapOver tp
+  }
+}